Friday’s Red Sox-Athletics matchups: Aaron Cook vs. Brandon McCarthy

As the starting rotation continues to take form following the trade that sent Josh Beckett to the Dodgers, the Red Sox will send out sinkerballer Aaron Cook for his 13th start of the season as the team begins the second series of its West Coast road trip.

Heading into his sixth start of August, Cook (3-7, 4.76 ERA) looks for a strong finish to a month in which he became a regular in the rotation after making just seven starts through July. Cook’s last start came against Kansas City on Aug. 25, when he received a no-decision after giving up three runs over six innings in a 10-9 Royals win.

Since pitching a complete-game shutout in June, Cook has been a decent starter, but he has not dominated at any point and has seen his numbers decline. After posting an ERA of 2.66 in six starts throughout June and July, Cook has recorded an ERA of 5.14 in his five starts so far in August. He’s also given up an uncharacteristic eight walks this month after allowing just four in all of his starts prior.

Most of Cook’s experience against the A’s came from his July 16th start in Oakland, when he gave up all three runs in a 3-2 loss. It was only the third start of Cook’s career against the A’s, as he spent most of his career in the National League, leaving him with limited experience against Oakland’s lineup. That is, except for shortstop Stephen Drew and outfielder/designated hitter Jonny Gomes, both of whom have posted monster numbers against Cook. Drew, who regularly faced Cook in the NL, has an OPS of .969, including six extra base hits, against him. Gomes has an OPS of 1.714 and three home runs in 14 plate appearances against Cook, most of which came while he was in Cincinnati.

Starting opposite Cook will be a fellow sinkerballer: towering right-hander, Brandon McCarthy (7-5, 3.12 ERA). Since arriving in Oakland in 2011, the 6-foot-7 McCarthy has reinvented himself as a pitcher, virtually removing the four-seam fastball from of his repertoire in favor of a ground ball-inducing arsenal of mostly cutters and sinkers. The overhaul has been a game-changer for McCarthy, who boasts a 3.25 ERA in his time in Oakland as opposed to a 4.68 in previous three-year stint with the Rangers.

McCarthy is coming off of a strong start against the Rays, against whom he gave up a first-inning home run before shutting them down for the next six innings in a 4-2 Oakland win. This success came just five days after McCarthy was rocked by the Twins, who lit him up early to the tune of six runs over 3 1/3 innings. The start, however, was an aberration during a season in which McCarthy has been remarkably consistent. The start against the Twins marked the first time all season that McCarthy failed to go at least five innings in an outing and just the fourth time he surrendered four or more runs.

The Red Sox faced the 29-year-old McCarthy earlier this season on May 2, when Oakland pulled out a 4-2 win in which the right-hander surrendered one earned run on five hits and three walks in 6 2/3 innings. The start, however, was McCarthy’s first against the Red Sox since 2008, leaving him with a limited sample size against the current Red Sox lineup. In that limited exposure, though, McCarthy has dominated the Red Sox, holding them to a .169 batting average with just one extra base hit.